I too have faced this question. My Dad simplified it best, in my opinion. Prepare for things that are likely to occur and affect me. Ignore those threats that I can neither prevent, influence, or mitigate. Stay in God's path. He will have you where he needs you, doing what he needs you to be doing.

I am prepared and organized for the likely man made and natural events (hurricanes, tornadoes, flooding, nuke or haz chem accidents). I ignore that which I can't control (asteroids, super volcanoes, hostile alien invasion of the insectoids, etc).